Triggering output of a re-torque signal

Abstract

There is provided a method, a system and a computer program product for triggering output of a re-torque signal indicative of a recommendation to fasten bolts of at least one wheel. The method comprises receiving at least wheel speed signals of the at least one wheel of a vehicle, determining, on the basis of the wheel speed signals, first current wheel properties of the at least one wheel, retrieving, from a storage device, calibrated wheel properties of the at least one wheel determined over at least two calibration phases, the at least two calibration phases being separated by at least one first wheel change of the wheel and determining whether the wheel has undergone a second wheel change by comparing the first current wheel properties with the calibrated wheel properties of at least a latest calibration phase. In response to determining that the second wheel change of the wheel has occurred, the method comprises triggering output of the re-torque signal based on a predetermined distance and/or a predetermined time since the determined second wheel change.

What is claimed is: 
     
         1 . A method for triggering output of a re-torque signal indicative of a recommendation to fasten bolts of at least one wheel, the method comprising:
 receiving at least wheel speed signals of the at least one wheel of a vehicle;   determining, on the basis of the wheel speed signals, first current wheel properties of the at least one wheel;   retrieving, from a storage device, calibrated wheel properties of the at least one wheel determined over at least two calibration phases, the at least two calibration phases being separated by at least one first wheel change of the wheel;   determining whether the wheel has undergone a second wheel change by comparing the first current wheel properties with the calibrated wheel properties of at least a latest calibration phase; and   in response to determining that the second wheel change of the wheel has occurred:   triggering output of the re-torque signal based on a predetermined distance and/or a predetermined time since the determined second wheel change.   
     
     
         2 . A method according to  claim 1 , further comprising:
 receiving timestamped sensor data such as controller area network, CAN, signals in connection with the wheel speed signals.   
     
     
         3 . A method according to  claim 1 , wherein determining whether the second wheel change has occurred is based on a deviation between the first current wheel properties and the calibrated wheel properties, wherein the deviation is a range or ratio that is adjustable. 
     
     
         4 . A method according to  claim 1 , further comprising:
 initiating a new calibration phase after determining that the second wheel change has occurred by
 stopping determination of the first current wheel properties of the at least one wheel in a current calibration phase; 
 storing the first current wheel properties for the current calibration phase as calibrated wheel properties of the at least one wheel in the storage device; and 
 starting determination of new current wheel properties in the new calibration phase after the second wheel change. 
   
     
     
         5 . A method according to  claim 4 , further comprising:
 clear at least some of the stored calibrated wheel properties.   
     
     
         6 . A method according to  claim 1 , wherein the re-torque signal is outputted in response to determining that the vehicle has been driven over the predetermined distance and/or the predetermined time since the determined second wheel change. 
     
     
         7 . A method according to  claim 6 , wherein
 the predetermined distance since the determined second wheel change is in the range of 1-250 km, particularly in the range of 1-150 km, more particularly in the range of 50-100 km; and/or   the predetermined time since the determined second wheel change is in the range of 1-4 weeks, particularly in the range of 1-2 weeks.   
     
     
         8 . A method according to  claim 1 , wherein the first current wheel properties of the at least one wheel comprises:
 properties determined by an indirect tire pressure monitoring system, such as tire vibration frequency, slip slope, relative and/or absolute tire radii, vibration energy, Fourier Transform properties; and/or   GPS signals for roll radius estimation, GPS time-stamp info; and/or   finger printing of the at least one wheel using machine learning on the wheel speed signals.   
     
     
         9 . A method according to  claim 1 , further comprising:
 determining second current wheel properties of the at least one wheel, based on at least the received wheel speed signals;   determine, on the basis of the second current wheel properties, that the at least one wheel is a loose wheel in order to obtain information about a status of the wheel's bolts; and   on the basis of the information about the status of the wheel's bolts:   outputting a preceding re-torque signal before the re-torque signal.   
     
     
         10 . A method according to  claim 9 , wherein the second current wheel properties of the at least one wheel are based on the received wheel speed signal. 
     
     
         11 . A method according to  claim 9 , wherein the preceding re-torque signal is outputted based on
 estimating a time and/or distance for an upcoming re-torque where the wheels bolts are expected to be loose;   determining whether the at least one wheel is a loose wheel;   outputting, in response to determining that the at least one wheel is a loose wheel, the preceding re-torque signal to expedite issuance of re-torque necessity of the bolts of the at least one wheel.   
     
     
         12 . A method according to  claim 9 , wherein the re-torque signal and the preceding re-torque signal serve as an indication for a driver of the vehicle to re-torque the bolts of the at least one wheel after the determined second wheel change. 
     
     
         13 . A system for triggering a re-torque signal to be outputted, comprising:
 a storage device configured to store calibrated wheel properties and comprising a processing unit,   wherein the processing unit is configured to perform steps including:   receiving at least wheel speed signals of the at least one wheel of a vehicle;   determining, on the basis of the wheel speed signals, first current wheel properties of the at least one wheel;   retrieving, from a storage device, calibrated wheel properties of the at least one wheel determined over at least two calibration phases, the at least two calibration phases being separated by at least one first wheel change of the wheel;   determining whether the wheel has undergone a second wheel change by comparing the first current wheel properties with the calibrated wheel properties of at least a latest calibration phase; and   in response to determining that the second wheel change of the wheel has occurred:   triggering output of the re-torque signal based on a predetermined distance and/or a predetermined time since the determined second wheel change.   
     
     
         14 . (canceled) 
     
     
         15 . A computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out steps that comprise:
 receiving at least wheel speed signals of the at least one wheel of a vehicle;   determining, on the basis of the wheel speed signals, first current wheel properties of the at least one wheel;   retrieving, from a storage device, calibrated wheel properties of the at least one wheel determined over at least two calibration phases, the at least two calibration phases being separated by at least one first wheel change of the wheel;   determining whether the wheel has undergone a second wheel change by comparing the first current wheel properties with the calibrated wheel properties of at least a latest calibration phase; and   in response to determining that the second wheel change of the wheel has occurred:   triggering output of the re-torque signal based on a predetermined distance and/or a predetermined time since the determined second wheel change.   
     
     
         16 . The computer-readable storage medium of  claim 15 , wherein the computer-readable storage medium includes a computer program product including the instructions.